Thread: No Park, Drive or Reverse

Havn't been on here for a few years since I sold my last GP, Recently picked up a 04 GTP Comp G with a supposedly bad trans, It has no drive, reverse or park, was hoping maybe a bad drive axle, Nope, so thinking the diff has gone. Trans was rebuilt about 35 to 40 thousand miles ago. Hoping replacing the diff will cure it, but afraid as to how much metal may have gone through the trans, Vehicle has been run maybe 1/2 hour total since it went bad. Need your advise if replacement of the diff will work or should I replace or rebuild the trans to be safe. Your input and help is appreciated.

Originally Posted by bcracing

Havn't been on here for a few years since I sold my last GP, Recently picked up a 04 GTP Comp G with a supposedly bad trans, It has no drive, reverse or park, was hoping maybe a bad drive axle, Nope, so thinking the diff has gone. Trans was rebuilt about 35 to 40 thousand miles ago. Hoping replacing the diff will cure it, but afraid as to how much metal may have gone through the trans, Vehicle has been run maybe 1/2 hour total since it went bad. Need your advise if replacement of the diff will work or should I replace or rebuild the trans to be safe. Your input and help is appreciated.

Sorry to say you need a trans, can't see how a diff will cause that

Thanks Logan, Was thinking the same thing, but park is a mechanical action not a hydraulic action, and my understanding is the parking pawl is located on the drum that houses the diff, granted I'm not real familiar with frnt wheel drive transmission, so my thinking may be way out of line.

I can't think of one sure fire issue that would cause all those symptoms. My guess is that it's more than one thing and that transmission fragged hard! One thing to keep in mind when replacing the transmission is that you have a special tap-shift transmission with 3.29 gear ratio so you 100% cannot swap a regular 4T65E in without tuning (maybe a stock non hd would work if you changed the passenger side axle but you'd loose tap shift, and not sure if the wiring is plug and play on those).

The good news if you end up rebuilding yourself is that there is nothing "magical" about these transmissions. The differential is a regular old hd diff just like the gtp trans. Only difference is the gear ratio is the same as the gt. Some of the gears might be hardened, but having taken one of these apart, I'm not convinced of this, everything looked the same. The only thing you need to swap to convert a regular 4T65E 3.29 from a gt into a comp-g is the differential from a gtp (hd), the valve body, channel plate, and wire harness from your comp-g. The reason I mention the ability to swap this is that you could be easier to rebuild a regular gt 4T65E and swap these parts than deal with the explosion that is probably the inside of your transmission. You will 100% want to inspect and check all the valves on both the valve body and channel plate and clean everything. There's a wonderful how to video on ebay that literally tells you step by step how to do this, and you only need two special tools (think they cost me $50 total off ebay) to compress the pistons and seat the new lip seals. Good luck!

Thanks for the info guys, When it is put in gear I can hear the trans spinning, ( why at first I thought drive axle) but after jacking it up and spinning the wheels, both axle turn into the transaxle, so not a axle shaft, and there is a grinding noise. When I go to put it back in park it sounds like putting a vehicle in park while its still moving.

Grab each axle where it enters the transmission and see if you can pull it out, or if it is very loose, (car off, not running) I have seen the splines break off inside the transmission before. Do you park on inclines or steep driveways?

Thanks Quicksilver, I'll check that out, As to parking on a incline, I'm not sure, but don't think it was as it has spent most of its life here on the coast of NC

Thanks for all the advice everyone. Check the drive axles like Quicksilver suggested, no luck. with it in park, Can hear the output shaft turning when i spin the drivers wheel and sounds like someone cracking nuts on the passengers side, and catches after about one revolution, but turns back the opposite way about one revolution then catchs will turn more if I give it a little tug. passenger side does same thing. Looks like its trans shopping time. Only paid $400 for it figuring it was going to need one, was just hoping it would be something easier.

Sounds like shattered spider gears in the diff.

Originally Posted by bcracing

Thanks for all the advice everyone. Check the drive axles like Quicksilver suggested, no luck. with it in park, Can hear the output shaft turning when i spin the drivers wheel and sounds like someone cracking nuts on the passengers side, and catches after about one revolution, but turns back the opposite way about one revolution then catchs will turn more if I give it a little tug. passenger side does same thing. Looks like its trans shopping time. Only paid $400 for it figuring it was going to need one, was just hoping it would be something easier.

Just make sure you see my post above. You cannot simply plug and play a non-comp-g 4T65E without programming. A lot of comp-g owners make that mistake